1. Field of the Invention
The invention relates to coupling and braking device for rail supported transportation equipment, particularly tow cars.
2. Description of the Prior Art
U.S. Pat. No. 3,636,884 suggests tow cars which are guided along a floor groove by means of drive rods arranged at their front end and which are entrained by an underfloor tow chain, each car having rigid front and rear fenders and a substantially horizontally guided movable front fender. In its rest position, the movable fender extends forwardly beyond the rigid front fender. When a tow car runs up against a stationary stop barrier or against a standing tow car, its drive rod is disengaged from the drive chain. A latching device for the movable fender of the succeeding car is at the same time displaced from its forward rest position into a rearward activated position.
This known design has the shortcoming of having a comparatively strong dependency on manufacturing tolerances, due to the requirement that the backlash brake be actuated at the same instant at which the drive rod is disengaged. In order to ascertain that the drive rod is safely disengaged upon runup of the tow car and, for this purpose, to assure that the linkage mechanism of the movable fender is displaced far enough, it is necessary that the kinematic energy of the tow car be of sufficient magnitude. It follows from this that the tow cars will impact against each other substantially without prior deceleration, meaning that elevated forces are generated between cars, which are incompatible with tow cars loaded with piece goods.
A further disadvantage relates to the fact that, immediately upon impact, an initial reverse movement of the car takes place, until the backlash brake takes full effect. Because of the tight tolerances involved, it may happen at this moment that the drive rod is again engaged with the drive chain, which may have destructive consequences.